Novel Ring Systems: Spiro[Cycloalkane] Derivatives of Triazolo- and Tetrazolo-Pyridazines.

In orderto synthesize new pyridazine derivatives anellated with different nitrogen heterocyclic moieties, spiro[cycloalkane]pyridazinones were transformed into the corresponding thioxo derivatives via a reaction with phosphorus pentasulfide. The reaction of the formed 2,3-diazaspiro[5.5] undec-3-ene-1-thiones with hydrazine provided the corresponding 1-hydrazono-2,3-diazaspiro[5.5] undec-3-ene, whose diazotization led to the desired spiro[cyclohexane-1,8'-tetrazolo[1,5-b]pyridazines. The reaction of dihydropyridazinethiones with benzhydrazide afforded the corresponding 7H-spiro[[1,2,4]triazolo[4,3-b]pyridazin-8,1'-cyclohexanes]. As a result of our work, seven new pyridazinethione intermediates were prepared, which served as starting materials for the synthesis of two kinds of new ring systems: tetrazolo-pyridazines and triazolo-pyridazines. The six new annulated derivatives were characterized by physicochemical parameters. The new N-heterocycles are valuable members of the large family of pyridazines.

Biomimetic synthesis and HPLC-ECD analysis of the isomers of dracocephins A and B.

Starting from racemic naringenin ((±)-1), a mixture of dracocephin A stereoisomers 6-(2"-pyrrolidinone-5"-yl)naringenin (±)-2a-d and its regioisomer, dracocephin B 8-(2"-pyrrolidinone-5"-yl)naringenin (±)-3a-d originally isolated from Dracocephalum rupestre, have been synthesized in a one-pot reaction. The separation of 2a-d and 3a-d was achieved by preparative HPLC. The four stereoisomers of each natural product were separated by analytical chiral HPLC and their absolute configuration was studied by the combination of HPLC-ECD measurements and TDDFT-ECD calculations. The synthesized flavonoid alkaloids were further characterized by physicochemical and in vitro pharmacological studies.

P2X3 and P2X2/3 receptor antagonists.

This review provides a concise summary of the molecular properties of the ligand-gated P2X receptors, in particular those containing the X3 subunit, as well as an overview comprising the most important patent applications on P2X3 and P2X2/3 receptor antagonists published since 2001. This review is mainly focused on small molecules with P2X3 and/or P2X2/3 antagonist properties. The most important classes of the patented compounds and conditions frequently claimed as their therapeutic targets are also discussed. Moreover, biological activity data from the cited patents and general prediction of druglikeness of the claimed compounds are also provided.

Recent advancements in anti-migraine drug research: focus on attempts to decrease neuronal hyperexcitability.

Migraine is a painful, sometimes debilitating disorder, which is frequently associated with various neurological symptoms. Its prevalence in the population is higher than that of any other neurological disorders, thus the burden of this disease on society is considerable. Although the introduction of triptans nearly two decades ago revolutionized the treatment of the disease there is still a huge unmet need regarding drugs with better properties. Formerly, migraine therapy primarily aimed at treating the pathological alterations of meningeal blood vessels that are thought to directly initiate a migraine headache attack. By now, it has been increasingly recognized by drug companies that abnormal neural function may be more important in the development of the disease and also in triggering an attack. Migraine is associated with an increased neuronal excitability and episodes of cortical spreading depression. Understanding the molecular mechanisms underlying the abnormal functioning of over-activated neuronal circuits may help to identify novel anti-migraine drug targets. Besides a general description of the pathophysiology and pharmacotherapy of migraine this review paper aims at discussing the possible drug targets through which migraine-related hyperexcitability and over-excitation can be attenuated. It will be shown how these new ideas appear in the recent patent literature.

Blockers of voltage-gated sodium channels for the treatment of central nervous system diseases.

Voltage gated sodium channels play important roles both in vital physiological functions and several pathological processes of the central nervous system. Epilepsy, chronic pain, neurodegenerative diseases, and spasticity are all characterized by an over-excited state of specific groups of central neurons that is accompanied by an abnormally increased activity of sodium channels. An efficient strategy of controlling such diseases is to use blockers that preferentially act on these over-excited cells. State dependently acting agents, such as phenytoin, or lamotrigine, leave normal physiological functions relatively intact, resulting in a favorable therapeutic window. Nine isoforms of the channel forming alpha subunit are known, which show distinct expression patterns in different tissues. Another possible way to decrease the chance of adverse effects is to develop agents selectively inhibiting the channel subtype involved in the pathomechanism of the disease to be treated. Many recent patents claim sodium channel blockers with improved characteristics regarding state dependency or subtype selectivity. Such agents may offer a breakthrough in the treatment of a variety of central nervous system diseases. This review focuses on the current trends in sodium channel research, surveying the traditional and newly emerging therapeutic fields, and the diverse medicinal chemistry of sodium channel blockers.